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California Water Science Center (CAWSC) - Groundwater Ambient Monitoring and Assessment (GAMA) Program

About GAMA

Who is GAMA?

Why is GAMA important?

What will participants gain from the GAMA program?

Study approach

GAMA program results reporting and contact information



Who is GAMA?

Crew sampling well in Southern California

Stewardship of the State’s ground-water resources is a shared responsibility between all levels of the government and community. Participants include representatives from California Water Boards (SWRCB/RWQCB), Department of Water Resources (DWR), Department of Health Services (DHS), U.S. Geological Survey (USGS), Lawrence Livermore National Laboratory (LLNL), regional water management entities, and county and local water agencies. A key aspect of the GAMA program is interagency collaboration and cooperation with local water agencies and well owners. Local participation in the GAMA program is entirely voluntary.

Why is GAMA important?

Well in Southern California

The GAMA program is important because the data collected during the study include analyses for chemical constituents that are not normally available; these data will be especially useful for providing an early indication of potential water-quality problems. The data also will be used to identify the natural and human factors affecting ground-water quality. An understanding of these factors is important for the long term management and protection of California's ground-water resources.

What Will Participants Gain from the GAMA Program?

The GAMA program will provide many benefits to State, local, and community participants. The program will

Study Approach

Priority Basins San Diego Desert Basin & Range Sierra Nevada Cascades & Modoc Plateau Klamath Mountains N Coast Ranges Central Valley S Coast Ranges Transverse & Selected Penninsular Ranges

There are 476 identified ground-water basins and subbasins in California (Belitz and others, 2003). For the purposes of this study, these ground-water basins were ranked in groups of sampling priority on the basis of the number of public-supply wells, ground-water usage, and potential sources of ground-water contamination (for example, leaking underground fuel tanks or pesticide applications) in each basin. The 116 identified priority basins collectively include more than 75 percent of the public-supply wells in California. For the GAMA program, the priority basins were combined into 35 study units. These study units will be sampled 2004 through 2010. In each study unit, 60 to 120 public-supply wells will be sampled.

Three types of water-quality assessments will be conducted for each study unit:

  1. Status: the assessment of current ground-water quality
  2. Trends: the detection of changes in water quality
  3. Understanding: the assessment of natural and human factors that affect ground-water quality

These assessments will integrate existing water-quality data (such as DHS public supply well water-quality data), with data collected specifically as part of this study. In addition, the GAMA program will monitor a much broader suite of constituents, at much lower detection limits, than required by DHS. Samples will be analyzed for chemical constituents that include major ions, trace elements, nutrients, volatile organic compounds, pesticides, and pharmaceuticals, to define the quality of water in the ground-water basins. Naturally occurring isotopes (tritium, carbon-14, and helium-4) also will be measured in these samples to help identify the source and age of the sampled ground water. A tiered analytical approach will be used to balance spatial coverage and analytical intensity (number of constituents analyzed).

GAMA Program Results Reporting

The GAMA program is committed to facilitating interagency communication and data sharing. Preliminary results will be discussed with participants at the local Groundwater Basin Assessment “Wrap- Up” meetings. The SWRCB and USGS will post a summary data report on the program Internet web-site, to be followed by the Groundwater Basin Assessment report. Prior to the public release of any data or reports, the SWRCB and USGS will consult with local water agencies and well owners to ensure that information is communicated in an appropriate manner. The SWRCB and the USGS will provide additional explanation of results upon request.

Contact Information

Technical reports and hydrologic data collected for the GAMA program may be obtained from:

GAMA Project ChiefPicture of oak tree
U.S. Geological Survey
California Water Science Center
4165 Spruance Road, Suite 200
San Diego, CA 92101
Telephone number: (619) 225-6100

GAMA Program Unit
State Water Resources Control Board
Division of Water Quality
PO Box 2231
Sacramento, CA 95812
Telephone number: (916) 341-5250

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URL: http://ca.water.usgs.gov/projects/gama/includes/GAMA_facts.html
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Page Last Modified: Wednesday, 09-Jan-2013 17:49:58 EST